This section provides background information related to the present disclosure which is not necessarily prior art.
Inside an injector drive controller, an injection driving device and/or an injector driver a clock signal is used for controlling the different functionalities of the controller and/or of the injector driver. One possible functionality may be provision of a control signal for an injector, and/or an injector needle. For this purpose, an actual injector driver may use an external clock signal generated by an external clock source. In general, a microcontroller may provide the external clock signal to the injection driving device. The injection driving device may condition the external clock signal and generate a signal for driving the injector. The injector driver may be connected to the injector which is the mechanical and/or electrical component acting according to the driving signals provided by the injector driver. The injector driver substantially hides the clock signals from the injector, since the injector driver is located between the external clock source and the injector.
Inside the injector driver a clock signal monitoring apparatus or an internal clock unit is provided to handle the clock signals. For safety reason in addition to the received external clock signal, the controller and/or injector driver may generate an internal clock signal in the clock signal monitoring apparatus. In this way, the internal clock signal may be used to monitor and/or to verify the external clock signal. In addition, the injector driver may use an internal clock source which generates the internal clock signal as a backup clock source in case of detecting faulty conditions in any of the clock signals. In an example, the internal clock source is located inside the clock signal monitoring apparatus or inside the internal clock unit. In particular, actual devices for driving an injector of an engine are equipped with such an internal clock which may be used to detect a faulty external clock signal.
However, the internal clock signal generated by the internal clock source may be assumed as to be more reliable than the external clock signal. Therefore, an actual control strategy may provide for always switching to the internal clock signal when any discrepancy between the external clock signal and the internal clock signal is detected. In this control strategy, the external clock signal may be always considered as to be defective when an error will appear. If the external clock is considered as to be faulty, the injector driver switches over to the internal clock in order to drive a respective automotive component, such as the injector. If, however, the injector driver may be predetermined to always switch to the internal clock after detecting faulty conditions, the controller or injector driver may switch to the internal clock signal and/or to the internal clock, even in cases where the internal clock signal is the source for the signal discrepancy. But, using the erroneous internal clock signal may result in missing injections. Missing injections may cause the engine to work inefficiently, to use the wrong quantity of injected fuel, to generate a wrong pulse width and/or may cause the engine to stall.
Accordingly, it is desirable to provide an efficient engine control strategy. In addition, it is desirable to detect a defective internal clock signal. Furthermore, it is desirable to detect an erroneous internal clock signal independently from the external clock signal. It is also desired to decide which one of two clock signals may be the defective signal. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.